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Addressing climate change is essential and possible, and it offers a host of benefits - from better public health to new economic opportunities. The United States has a historic opportunity to lead the way in decarbonization by transforming its current energy system to one with net-zero emissions of carbon dioxide. Recent legislation has set the nation on the path to reach its goal of net zero by 2050 in order to avoid the worst consequences of climate change. However, even if implemented as designed, current policy will get the United States only part of the way to its net-zero goal. Accelerating Decarbonization in the United States provides a comprehensive set of actionable recommendations to help policymakers achieve a just and equitable energy transition over the next decade and beyond, including policy, technology, and societal dimensions. This report addresses federal and subnational policy needs to overcome implementation barriers and gaps with a focus on energy justice, workforce development, public health, and public engagement. The report also presents a suite of recommendations for the electricity, transportation, built environment, industrial, fossil fuels, land use, and finance sectors.

As part of its responsibilities under the Clean Air Act, the U.S. Environmental Protection Agency sets National Ambient Air Quality Standards (NAAQS) for the air pollutants carbon monoxide, lead, oxides of nitrogen, particulate matter, ozone, and sulfur dioxide. EPA uses a'weight of evidence approach'to evaluate evidence from scientific studies and describe the causal relationships between these'criteria pollutants'and any adverse impacts on human health and on public welfare - including impacts on wildlife, water, forests, agriculture, and climate. The evaluation, called an Integrated Science Assessment, is used to inform standards setting associated with the criteria pollutants. This report, produced at the request of EPA, describes EPAs and several other frameworks for inferring causality of health or welfare effects and the characteristics of evidence useful for forming a causal determination. The report concludes that EPAs causal framework is effective, reliable, and scientifically defensible, provided that key scientific questions are identified and a range of necessary expertise is engaged. More transparency in how EPA integrates evidence could improve confidence in their determinations, and more guidance is needed in the framework on how evidence should be examined for vulnerable groups (e.g., human sub-populations) and sensitive ecosystems or species.

Climate change, driven by increases in human-produced greenhouse gases and particles (collectively referred to as GHGs), is the most serious environmental issue facing society. The need to reduce GHGs has become urgent as heat waves, heavy rain events, and other impacts of climate change have become more frequent and severe. Since the Paris Agreement was adopted in 2015, more than 136 countries, accounting for about 80% of total global GHG emissions, have committed to achieving net-zero emissions by 2050. A growing number of cities, regional governments, and industries have also made pledges to reduce emissions. Providing decision makers with useful, accurate, and trusted GHG emissions information is a crucial part of this effort. This report examines existing and emerging approaches used to generate and evaluate GHG emissions information at global to local scales. The report develops a framework for evaluating GHG emissions information to support and guide policy makers about its use in decision making. The framework identifies six criteria or pillars that can be used to evaluate and improve GHG emissions information: usability and timeliness, information transparency, evaluation and validation, completeness, inclusivity, and communication. The report recommends creating a coordinated repository or clearinghouse to operationalize the six pillars, for example, by providing timely, transparent, traceable information; standardized data formats; and governance mechanisms that are coordinated, trusted, and inclusive of the global community.

More intense heat waves, extended wildfire seasons and other escalating impacts of climate change have made it more important than ever to fill knowledge gaps that improve society's understanding, assessment, and response to global change. The US Global Change Research Program (USGCRP) - a collection of 13 Federal entities charged by law to help the United States and the world fill those knowledge gaps - laid out proposed mechanisms and priorities for global change research over the next decade in its draft Decadal Strategic Plan 2022-2031. The draft plan recognizes that priority knowledge gaps have shifted over the past decade as demand has grown for more useful and more inclusive data to inform decision-making, and as the focus on resilience and sustainability has increased. As part of its work in advising the USGCRP since 2011, the National Academies reviewed USGCRP's draft plan to determine how it might be enhanced. Advances in the draft plan include an increased emphasis on social sciences, community engagement with marginalized groups, and promotion of diversity, equity, inclusion, and justice in the production of science. Strengthening the interconnections between the plan's core pillars and expanding opportunities for coordination among federal agencies tasked with responding to global climate change would improve the plan. The draft plan could more strongly convey a sense of urgency throughout the plan and would benefit from additional examples of key research outputs that could advance policy and decision making on global change challenges.

Wildland fires pose a growing threat to air quality and human health. Fire is a natural part of many landscapes, but the extent of area burned and the severity of fires have been increasing, concurrent with human movement into previously uninhabited fire-prone areas and forest management practices that have increased fuel loads. These changes heighten the risk of exposure to fire itself and emissions (smoke), which can travel thousands of miles and affect millions of people, creating local, regional, and national air quality and health concerns. To address this growing threat, the National Academies brought together atmospheric chemistry and health research communities, natural resource managers, and decision makers to discuss current knowledge and needs surrounding how wildland fire emissions affect air quality and human health. Participants also explored opportunities to better bridge these communities to advance science and improve the production and exchange of information. This publication summarizes the workshop discussions and themes that emerged throughout the meeting.

Sediments, ice, corals, and trees are just some of the natural storehouses of information that help tell the complicated history of Earth's climate. Paleoclimate researchers use these'proxies,'in combination with numerical models, to gain understanding of the magnitudes, rates, and drivers of past climate variability with the goal of informing understanding of current and future change in Earth's climate system. The Paleo Perspectives on Climate Change (P2C2) program of the National Science Foundation (NSF) has advanced paleoclimate research through proxy development, data-model comparisons, and synthesis work, and has facilitated interdisciplinary collaboration that has contributed to the growth of the field. This new publication highlights discussions at a June 2021 workshop that focused on identifying potential future paleoclimate research directions to further advance understanding of past climate and better inform the public and decision makers about the expected future.

The National Aeronautics and Space Administration (NASA) and other U.S. science research agencies operate a fleet of research aircraft and other airborne platforms that offer diverse capabilities. To inform NASA's future investments in airborne platforms, this study examines whether a large aircraft that would replace the current NASA DC-8 is needed to address Earth system science questions, and the role of other airborne platforms for achieving future Earth system science research goals.

Climate change is creating impacts that are widespread and severe for individuals, communities, economies, and ecosystems around the world. While efforts to reduce emissions and adapt to climate impacts are the first line of defense, researchers are exploring other options to reduce warming. Solar geoengineering strategies are designed to cool Earth either by adding small reflective particles to the upper atmosphere, by increasing reflective cloud cover in the lower atmosphere, or by thinning high-altitude clouds that can absorb heat. While such strategies have the potential to reduce global temperatures, they could also introduce an array of unknown or negative consequences. This report concludes that a strategic investment in research is needed to enhance policymakers'understanding of climate response options. The United States should develop a transdisciplinary research program, in collaboration with other nations, to advance understanding of solar geoengineering's technical feasibility and effectiveness, possible impacts on society and the environment, and social dimensions such as public perceptions, political and economic dynamics, and ethical and equity considerations. The program should operate under robust research governance that includes such elements as a research code of conduct, a public registry for research, permitting systems for outdoor experiments, guidance on intellectual property, and inclusive public and stakeholder engagement processes.

To achieve goals for climate and economic growth,'negative emissions technologies'(NETs) that remove and sequester carbon dioxide from the air will need to play a significant role in mitigating climate change. Unlike carbon capture and storage technologies that remove carbon dioxide emissions directly from large point sources such as coal power plants, NETs remove carbon dioxide directly from the atmosphere or enhance natural carbon sinks. Storing the carbon dioxide from NETs has the same impact on the atmosphere and climate as simultaneously preventing an equal amount of carbon dioxide from being emitted. Recent analyses found that deploying NETs may be less expensive and less disruptive than reducing some emissions, such as a substantial portion of agricultural and land-use emissions and some transportation emissions. In 2015, the National Academies published Climate Intervention: Carbon Dioxide Removal and Reliable Sequestration, which described and initially assessed NETs and sequestration technologies. This report acknowledged the relative paucity of research on NETs and recommended development of a research agenda that covers all aspects of NETs from fundamental science to full-scale deployment. To address this need, Negative Emissions Technologies and Reliable Sequestration: A Research Agenda assesses the benefits, risks, and'sustainable scale potential'for NETs and sequestration. This report also defines the essential components of a research and development program, including its estimated costs and potential impact.

Emissions associated with oil and gas exploration, development, and production on the Gulf waters can result in increased levels of air pollutants that contribute to a range of air quality impacts in the Gulf of Mexico Region (GOMR).'Criteria air pollutants', such as carbon monoxide, lead, nitrogen dioxide, ozone, particulate matter, and sulfur dioxide, are considered harmful to public health and the environment. The Bureau of Ocean Energy Management (BOEM) manages the U.S. outer continental shelf oil and gas resources and is required to help manage air quality in the GOMR. Review of the Bureau of Ocean Energy Management'Air Quality Modeling in the Gulf of Mexico Region'Study reviews and provides feedback on the BOEM's Air Quality Modeling in the Gulf of Mexico Region Study. This independent technical review of the study explores whether the study meets its goals, accurately reflects the scientific literature, uses reasonable data and modeling analyses, approaches quantitative modeling appropriately, documents findings in a consistent, transparent, and credible way, and aligns with necessary guidelines.

In the quest to mitigate the buildup of greenhouse gases in Earth's atmosphere, researchers and policymakers have increasingly turned their attention to techniques for capturing greenhouse gases such as carbon dioxide and methane, either from the locations where they are emitted or directly from the atmosphere. Once captured, these gases can be stored or put to use. While both carbon storage and carbon utilization have costs, utilization offers the opportunity to recover some of the cost and even generate economic value. While current carbon utilization projects operate at a relatively small scale, some estimates suggest the market for waste carbon-derived products could grow to hundreds of billions of dollars within a few decades, utilizing several thousand teragrams of waste carbon gases per year. Gaseous Carbon Waste Streams Utilization: Status and Research Needs assesses research and development needs relevant to understanding and improving the commercial viability of waste carbon utilization technologies and defines a research agenda to address key challenges. The report is intended to help inform decision making surrounding the development and deployment of waste carbon utilization technologies under a variety of circumstances, whether motivated by a goal to improve processes for making carbon-based products, to generate revenue, or to achieve environmental goals.

Climate change poses many challenges that affect society and the natural world. With these challenges, however, come opportunities to respond. By taking steps to adapt to and mitigate climate change, the risks to society and the impacts of continued climate change can be lessened. The National Climate Assessment, coordinated by the U.S. Global Change Research Program, is a mandated report intended to inform response decisions. Required to be developed every four years, these reports provide the most comprehensive and up-to-date evaluation of climate change impacts available for the United States, making them a unique and important climate change document. The draft Fourth National Climate Assessment (NCA4) report reviewed here addresses a wide range of topics of high importance to the United States and society more broadly, extending from human health and community well-being, to the built environment, to businesses and economies, to ecosystems and natural resources. This report evaluates the draft NCA4 to determine if it meets the requirements of the federal mandate, whether it provides accurate information grounded in the scientific literature, and whether it effectively communicates climate science, impacts, and responses for general audiences including the public, decision makers, and other stakeholders.

The second'State of the Climate Cycle Report'(SOCCR2) aims to elucidate the fundamental physical, chemical, and biological aspects of the carbon cycle and to discuss the challenges of accounting for all major carbon stocks and flows for the North American continent. This assessment report has broad value, as understanding the carbon cycle is not just an academic exercise. Rather, this understanding can provide an important foundation for making a wide variety of societal decisions about land use and natural resource management, climate change mitigation strategies, urban planning, and energy production and consumption. To help assure the quality and rigor of SOCCR2, this report provides an independent critique of the draft document.

Our ability to observe and forecast severe weather events has improved markedly over the past few decades. Forecasts of snow and ice storms, hurricanes and storm surge, extreme heat, and other severe weather events are made with greater accuracy, geographic specificity, and lead time to allow people and communities to take appropriate protective measures. Yet hazardous weather continues to cause loss of life and result in other preventable social costs. There is growing recognition that a host of social and behavioral factors affect how we prepare for, observe, predict, respond to, and are impacted by weather hazards. For example, an individual's response to a severe weather event may depend on their understanding of the forecast, prior experience with severe weather, concerns about their other family members or property, their capacity to take the recommended protective actions, and numerous other factors. Indeed, it is these factors that can determine whether or not a potential hazard becomes an actual disaster. Thus, it is essential to bring to bear expertise in the social and behavioral sciences (SBS)—including disciplines such as anthropology, communication, demography, economics, geography, political science, psychology, and sociology—to understand how people's knowledge, experiences, perceptions, and attitudes shape their responses to weather risks and to understand how human cognitive and social dynamics affect the forecast process itself. Integrating Social and Behavioral Sciences Within the Weather Enterprise explores and provides guidance on the challenges of integrating social and behavioral sciences within the weather enterprise. It assesses current SBS activities, describes the potential value of improved integration of SBS and barriers that impede this integration, develops a research agenda, and identifies infrastructural and institutional arrangements for successfully pursuing SBS-weather research and the transfer of relevant findings to operational settings.

The U.S. Global Change Research Program (USGCRP) is an interagency program, established by the Global Change Research Act (GCRA) of 1990, mandated by Congress to'assist the Nation and the world to understand, assess, predict, and respond to human-induced and natural processes of global change'. Since the USGCRP began, scientific understanding of global change has increased and the information needs of the nation have changed dramatically. A better understanding of what is changing and why can help decision makers in the public and private sectors cope with ongoing change. Accomplishments of the U.S. Global Change Research Program highlights the growth of global change science in the quarter century that the USGCRP has been in existence, and documents some of its contributions to that growth through its primary functions of interagency planning and coordination, and of synthesis of research and practice to inform decision making.

The United States Global Change Research Program (USGCRP) is moving towards a sustained assessment process that allows for more fluid and consistent integration of scientific knowledge into the mandated quadrennial National Climate Assessment. As part of this process, the USGCRP is developing the Climate Science Special Report (CSSR), a technical report that details the current state-of-science relating to climate change and its physical impacts. The CSSR is intended to focus on climate change in the United States and to inform future USGCRP products. Review of the Draft Climate Science Special Report assesses whether the draft CSSR accurately presents the scientific literature in an understandable, transparent and traceable way; whether the CSSR authors handled the data, analyses, and statistical approaches in an appropriate manner; and the effectiveness of the report in conveying the information clearly for the intended audience. This report provides recommendations for how the draft CSSR could be strengthened.

The ocean is an integral component of the Earth's climate system. It covers about 70% of the Earth's surface and acts as its primary reservoir of heat and carbon, absorbing over 90% of the surplus heat and about 30% of the carbon dioxide associated with human activities, and receiving close to 100% of fresh water lost from land ice. With the accumulation of greenhouse gases in the atmosphere, notably carbon dioxide from fossil fuel combustion, the Earth's climate is now changing more rapidly than at any time since the advent of human societies. Society will increasingly face complex decisions about how to mitigate the adverse impacts of climate change such as droughts, sea-level rise, ocean acidification, species loss, changes to growing seasons, and stronger and possibly more frequent storms. Observations play a foundational role in documenting the state and variability of components of the climate system and facilitating climate prediction and scenario development. Regular and consistent collection of ocean observations over decades to centuries would monitor the Earth's main reservoirs of heat, carbon dioxide, and water and provides a critical record of long-term change and variability over multiple time scales. Sustained high-quality observations are also needed to test and improve climate models, which provide insights into the future climate system. Sustaining Ocean Observations to Understand Future Changes in Earth's Climate considers processes for identifying priority ocean observations that will improve understanding of the Earth's climate processes, and the challenges associated with sustaining these observations over long timeframes.

Extremely hazardous substances can be released accidentally as a result of chemical spills, industrial explosions, fires, or accidents involving railroad cars and trucks transporting EHSs. Workers and residents in communities surrounding industrial facilities where these substances are manufactured, used, or stored and in communities along the nation's railways and highways are potentially at risk of being exposed to airborne EHSs during accidental releases or intentional releases by terrorists. Pursuant to the Superfund Amendments and Reauthorization Act of 1986, the U.S. Environmental Protection Agency (EPA) has identified approximately 400 EHSs on the basis of acute lethality data in rodents. Acute Exposure Guideline Levels for Selected Airborne Chemicals, Volume 20 reviews and updates the technical support document on acute exposure guideline levels (AEGLs) for selected chloroformates. This update focuses on establishing AEGL-3 values for n-propyl chloroformate and isopropyl chloroformate, but will also consider whether any new data are available that would affect the proposed values for the other 10 chloroformates. AEGLs represent threshold exposure limits (exposure levels below which adverse health effects are not likely to occur) for the general public and are applicable to emergency exposures ranging from 10 minutes (min) to 8 h. Three levels - AEGL-1, AEGL-2, and AEGL-3 - are developed for each of five exposure periods (10 min, 30 min, 1 h, 4 h, and 8 h) and are distinguished by varying degrees of severity of toxic effects. This report will inform planning, response, and prevention in the community, the workplace, transportation, the military, and the remediation of Superfund sites.

The US Global Change Research Program (USGCRP) is a collection of 13 Federal entities charged by law to assist the United States and the world to understand, assess, predict, and respond to human-induced and natural processes of global change. As the understanding of global change has evolved over the past decades and as demand for scientific information on global change has increased, the USGCRP has increasingly focused on research that can inform decisions to cope with current climate variability and change, to reduce the magnitude of future changes, and to prepare for changes projected over coming decades. Overall, the current breadth and depth of research in these agencies is insufficient to meet the country's needs, particularly to support decision makers. This report provides a rationale for evaluating current program membership and capabilities and identifying potential new agencies and departments in the hopes that these changes will enable the program to more effectively inform the public and prepare for the future. It also offers actionable recommendations for adjustments to the methods and procedures that will allow the program to better meet its stated goals.

Our world is changing at an accelerating rate. The global human population has grown from 6.1 billion to 7.1 billion in the last 15 years and is projected to reach 11.2 billion by the end of the century. The distribution of humans across the globe has also shifted, with more than 50 percent of the global population now living in urban areas, compared to 29 percent in 1950. Along with these trends, increasing energy demands, expanding industrial activities, and intensification of agricultural activities worldwide have in turn led to changes in emissions that have altered the composition of the atmosphere. These changes have led to major challenges for society, including deleterious impacts on climate, human and ecosystem health. Climate change is one of the greatest environmental challenges facing society today. Air pollution is a major threat to human health, as one out of eight deaths globally is caused by air pollution. And, future food production and global food security are vulnerable to both global change and air pollution. Atmospheric chemistry research is a key part of understanding and responding to these challenges. The Future of Atmospheric Chemistry Research: Remembering Yesterday, Understanding Today, Anticipating Tomorrow summarizes the rationale and need for supporting a comprehensive U.S. research program in atmospheric chemistry; comments on the broad trends in laboratory, field, satellite, and modeling studies of atmospheric chemistry; determines the priority areas of research for advancing the basic science of atmospheric chemistry; and identifies the highest priority needs for improvements in the research infrastructure to address those priority research topics. This report describes the scientific advances over the past decade in six core areas of atmospheric chemistry: emissions, chemical transformation, oxidants, atmospheric dynamics and circulation, aerosol particles and clouds, and biogeochemical cycles and deposition. This material was developed for the NSF's Atmospheric Chemistry Program; however, the findings will be of interest to other agencies and programs that support atmospheric chemistry research.

The United States'tradition of conserving fish, wildlife, habitats, and cultural resources dates to the mid-19th century. States have long sought to manage fish and wildlife species within their borders, whereas many early federal conservation efforts focused on setting aside specific places as parks, sanctuaries, or reserves. With advances in landscape ecology over the past quarter-century, conservation planners, scientists, and practitioners began to stress the importance of conservation efforts at the scale of landscapes and seascapes. These larger areas were thought to harbor relatively large numbers of species that are likely to maintain population viability and sustain ecological processes and natural disturbance regimes - often considered critical factors in conserving biodiversity. By focusing conservation efforts at the level of whole ecosystems and landscape, practitioners can better attempt to conserve the vast majority of species in a particular ecosystem. Successfully addressing the large-scale, interlinked problems associated with landscape degradation will necessitate a planning process that bridges different scientific disciplines and across sectors, as well as an understanding of complexity, uncertainty, and the local context of conservation work. The landscape approach aims to develop shared conservation priorities across jurisdictions and across many resources to create a single, collaborative conservation effort that can meet stakeholder needs. Conservation of habitats, species, ecosystem services, and cultural resources in the face of multiple stressors requires governance structures that can bridge the geographic and jurisdictional boundaries of the complex socio-ecological systems in which landscape-level conservation occurs. The Landscape Conservation Cooperatives (LCC) Network was established to complement and add value to the many ongoing state, tribal, federal, and nongovernmental efforts to address the challenge of conserving species, habitats, ecosystem services, and cultural resources in the face of large-scale and long-term threats, including climate change. A Review of the Landscape Conservation Cooperatives evaluates the purpose, goals, and scientific merits of the LCC program within the context of similar programs, and whether the program has resulted in measurable improvements in the health of fish, wildlife, and their habitats.

As climate has warmed over recent years, a new pattern of more frequent and more intense weather events has unfolded across the globe. Climate models simulate such changes in extreme events, and some of the reasons for the changes are well understood. Warming increases the likelihood of extremely hot days and nights, favors increased atmospheric moisture that may result in more frequent heavy rainfall and snowfall, and leads to evaporation that can exacerbate droughts. Even with evidence of these broad trends, scientists cautioned in the past that individual weather events couldn't be attributed to climate change. Now, with advances in understanding the climate science behind extreme events and the science of extreme event attribution, such blanket statements may not be accurate. The relatively young science of extreme event attribution seeks to tease out the influence of human-cause climate change from other factors, such as natural sources of variability like El Niño, as contributors to individual extreme events. Event attribution can answer questions about how much climate change influenced the probability or intensity of a specific type of weather event. As event attribution capabilities improve, they could help inform choices about assessing and managing risk, and in guiding climate adaptation strategies. This report examines the current state of science of extreme weather attribution, and identifies ways to move the science forward to improve attribution capabilities.

Many factors contribute to variability in Earth's climate on a range of timescales, from seasons to decades. Natural climate variability arises from two different sources: (1) internal variability from interactions among components of the climate system, for example, between the ocean and the atmosphere, and (2) natural external forcings, such as variations in the amount of radiation from the Sun. External forcings on the climate system also arise from some human activities, such as the emission of greenhouse gases (GHGs) and aerosols. The climate that we experience is a combination of all of these factors. Understanding climate variability on the decadal timescale is important to decision-making. Planners and policy makers want information about decadal variability in order to make decisions in a range of sectors, including for infrastructure, water resources, agriculture, and energy. In September 2015, the National Academies of Sciences, Engineering, and Medicine convened a workshop to examine variability in Earth's climate on decadal timescales, defined as 10 to 30 years. During the workshop, ocean and climate scientists reviewed the state of the science of decadal climate variability and its relationship to rates of human-caused global warming, and they explored opportunities for improvement in modeling and observations and assessing knowledge gaps. Frontiers in Decadal Climate Variability summarizes the presentations and discussions from the workshop.

As the nation's economic activities, security concerns, and stewardship of natural resources become increasingly complex and globally interrelated, they become ever more sensitive to adverse impacts from weather, climate, and other natural phenomena. For several decades, forecasts with lead times of a few days for weather and other environmental phenomena have yielded valuable information to improve decision-making across all sectors of society. Developing the capability to forecast environmental conditions and disruptive events several weeks and months in advance could dramatically increase the value and benefit of environmental predictions, saving lives, protecting property, increasing economic vitality, protecting the environment, and informing policy choices. Over the past decade, the ability to forecast weather and climate conditions on subseasonal to seasonal (S2S) timescales, i.e., two to fifty-two weeks in advance, has improved substantially. Although significant progress has been made, much work remains to make S2S predictions skillful enough, as well as optimally tailored and communicated, to enable widespread use. Next Generation Earth System Predictions presents a ten-year U.S. research agenda that increases the nation's S2S research and modeling capability, advances S2S forecasting, and aids in decision making at medium and extended lead times.

BioWatch is an air monitoring system deployed in jurisdictions around the country with the goal of detecting the presence of certain high risk pathogenic microorganisms. It relies on a network of federal and nonfederal collaborative relationships to be successful, and is one part of a larger array of disease surveillance, intelligence-gathering, and biomonitoring activities in support of public safety and health. The assays used in the BioWatch system to detect the presence of pathogens in collected samples rely on the technique of polymerase chain reaction (PCR) to sensitively and specifically amplify target nucleic acid sequences. BioWatch PCR Assays evaluates and provides guidance on appropriate standards for the validation and verification of PCR tests and assays in order to ensure that adequate performance data are available to public health and other key decision makers with a sufficient confidence level to facilitate the public health response to a BioWatch Actionable Response. This report discusses principles of performance standards, reviews information from several existing guidance documents and standards that might be applicable to BioWatch, and discusses assay testing efforts that have occurred or are ongoing. BioWatch PCR Assays provides recommendations on general principles and approaches for a performance standard and validation framework to meet BioWatch's mission. The report also considers how developments in technology, particularly in multiplex PCR and next-generation sequencing, can contribute to the ability of the BioWatch program to meet current and future challenges. This report has been determined to contain information exempt from disclosure under 5 U.S.C. 552(b). Section 15 of the Federal Advisory Committee Act provides that the National Academies shall make its final report available to the public unless the National Academies determines that the report would disclose matters described in one or more of the exemption provisions under the Freedom of Information Act (FOIA). In such case, the National Academies'shall make public an abbreviated version of the report that does not disclose those matters.'This unrestricted, abbreviated version of the report represents, in so far as possible, the committee's findings, recommendations, and other substantive material without disclosing materials described in 5 U.S.C. 552(b).

The growing problem of changing environmental conditions caused by climate destabilization is well recognized as one of the defining issues of our time. The root problem is greenhouse gas emissions, and the fundamental solution is curbing those emissions. Climate geoengineering has often been considered to be a'last-ditch'response to climate change, to be used only if climate change damage should produce extreme hardship. Although the likelihood of eventually needing to resort to these efforts grows with every year of inaction on emissions control, there is a lack of information on these ways of potentially intervening in the climate system. As one of a two-book report, this volume of Climate Intervention discusses albedo modification - changing the fraction of incoming solar radiation that reaches the surface. This approach would deliberately modify the energy budget of Earth to produce a cooling designed to compensate for some of the effects of warming associated with greenhouse gas increases. The prospect of large-scale albedo modification raises political and governance issues at national and global levels, as well as ethical concerns. Climate Intervention: Reflecting Sunlight to Cool Earth discusses some of the social, political, and legal issues surrounding these proposed techniques. It is far easier to modify Earth's albedo than to determine whether it should be done or what the consequences might be of such an action. One serious concern is that such an action could be unilaterally undertaken by a small nation or smaller entity for its own benefit without international sanction and regardless of international consequences. Transparency in discussing this subject is critical. In the spirit of that transparency, Climate Intervention: Reflecting Sunlight to Cool Earth was based on peer-reviewed literature and the judgments of the authoring committee; no new research was done as part of this study and all data and information used are from entirely open sources. By helping to bring light to this topic area, this book will help leaders to be far more knowledgeable about the consequences of albedo modification approaches before they face a decision whether or not to use them.

The signals are everywhere that our planet is experiencing significant climate change. It is clear that we need to reduce the emissions of carbon dioxide and other greenhouse gases from our atmosphere if we want to avoid greatly increased risk of damage from climate change. Aggressively pursuing a program of emissions abatement or mitigation will show results over a timescale of many decades. How do we actively remove carbon dioxide from the atmosphere to make a bigger difference more quickly? As one of a two-book report, this volume of Climate Intervention discusses CDR, the carbon dioxide removal of greenhouse gas emissions from the atmosphere and sequestration of it in perpetuity. Climate Intervention: Carbon Dioxide Removal and Reliable Sequestration introduces possible CDR approaches and then discusses them in depth. Land management practices, such as low-till agriculture, reforestation and afforestation, ocean iron fertilization, and land-and-ocean-based accelerated weathering, could amplify the rates of processes that are already occurring as part of the natural carbon cycle. Other CDR approaches, such as bioenergy with carbon capture and sequestration, direct air capture and sequestration, and traditional carbon capture and sequestration, seek to capture CO2 from the atmosphere and dispose of it by pumping it underground at high pressure. This book looks at the pros and cons of these options and estimates possible rates of removal and total amounts that might be removed via these methods. With whatever portfolio of technologies the transition is achieved, eliminating the carbon dioxide emissions from the global energy and transportation systems will pose an enormous technical, economic, and social challenge that will likely take decades of concerted effort to achieve. Climate Intervention: Carbon Dioxide Removal and Reliable Sequestration will help to better understand the potential cost and performance of CDR strategies to inform debate and decision making as we work to stabilize and reduce atmospheric concentrations of carbon dioxide.

Extremely hazardous substances can be released accidentally as a result of chemical spills, industrial explosions, fires, or accidents involving railroad cars and trucks transporting EHSs. Workers and residents in communities surrounding industrial facilities where these substances are manufactured, used, or stored and in communities along the nation's railways and highways are potentially at risk of being exposed to airborne EHSs during accidental releases or intentional releases by terrorists. Pursuant to the Superfund Amendments and Reauthorization Act of 1986, the U.S. Environmental Protection Agency (EPA) has identified approximately 400 EHSs on the basis of acute lethality data in rodents. Acute Exposure Guideline Levels for Selected Airborne Chemicals, Volume 18 identifies, reviews, and interprets relevant toxicologic and other scientific data for selected AEGL documents for bromine chloride, carbonyl fluoride, selected halogen fluorides, and oxygen difluoride in order to develop acute exposure guideline levels (AEGLs) for these high-priority, acutely toxic chemicals. AEGLs represent threshold exposure limits (exposure levels below which adverse health effects are not likely to occur) for the general public and are applicable to emergency exposures ranging from 10 minutes (min) to 8 h. Three levels - AEGL-1, AEGL-2, and AEGL-3 - are developed for each of five exposure periods (10 min, 30 min, 1 h, 4 h, and 8 h) and are distinguished by varying degrees of severity of toxic effects. This report will inform planning, response, and prevention in the community, the workplace, transportation, the military, and the remediation of Superfund sites.

Extremely hazardous substances can be released accidentally as a result of chemical spills, industrial explosions, fires, or accidents involving railroad cars and trucks transporting EHSs. Workers and residents in communities surrounding industrial facilities where these substances are manufactured, used, or stored and in communities along the nation's railways and highways are potentially at risk of being exposed to airborne EHSs during accidental releases or intentional releases by terrorists. Pursuant to the Superfund Amendments and Reauthorization Act of 1986, the U.S. Environmental Protection Agency (EPA) has identified approximately 400 EHSs on the basis of acute lethality data in rodents. Acute Exposure Guideline Levels for Selected Airborne Chemicals, Volume 19 identifies, reviews, and interprets relevant toxicologic and other scientific data for selected AEGL documents for cyanide salts, diketene, methacrylaldehyde, pentaborane, tellurium hexafluoride, and tetrafluoroethylene in order to develop acute exposure guideline levels (AEGLs) for these high-priority, acutely toxic chemicals. AEGLs represent threshold exposure limits (exposure levels below which adverse health effects are not likely to occur) for the general public and are applicable to emergency exposures ranging from 10 minutes (min) to 8 h. Three levels - AEGL-1, AEGL-2, and AEGL-3 - are developed for each of five exposure periods (10 min, 30 min, 1 h, 4 h, and 8 h) and are distinguished by varying degrees of severity of toxic effects. This report will inform planning, response, and prevention in the community, the workplace, transportation, the military, and the remediation of Superfund sites.

The Arctic has been undergoing significant changes in recent years. Average temperatures are rising twice as fast as they are elsewhere in the world. The extent and thickness of sea ice is rapidly declining. Such changes may have an impact on atmospheric conditions outside the region. Several hypotheses for how Arctic warming may be influencing mid-latitude weather patterns have been proposed recently. For example, Arctic warming could lead to a weakened jet stream resulting in more persistent weather patterns in the mid-latitudes. Or Arctic sea ice loss could lead to an increase of snow on high-latitude land, which in turn impacts the jet stream resulting in cold Eurasian and North American winters. These and other potential connections between a warming Arctic and mid-latitude weather are the subject of active research. Linkages Between Arctic Warming and Mid-Latitude Weather Patterns is the summary of a workshop convened in September 2013 by the National Research Council to review our current understanding and to discuss research needed to better understand proposed linkages. A diverse array of experts examined linkages between a warming Arctic and mid-latitude weather patterns. The workshop included presentations from leading researchers representing a range of views on this topic. The workshop was organized to allow participants to take a global perspective and consider the influence of the Arctic in the context of forcing from other components of the climate system, such as changes in the tropics, ocean circulation, and mid-latitude sea surface temperature. This report discusses our current understanding of the mechanisms that link declines in Arctic sea ice cover, loss of high-latitude snow cover, changes in Arctic-region energy fluxes, atmospheric circulation patterns, and the occurrence of extreme weather events; possible implications of more severe loss of summer Arctic sea ice upon weather patterns at lower latitudes; major gaps in our understanding, and observational and/or modeling efforts that are needed to fill those gaps; and current opportunities and limitations for using Arctic sea ice predictions to assess the risk of temperature/precipitation anomalies and extreme weather events over northern continents.

Extremely hazardous substances can be released accidentally as a result of chemical spills, industrial explosions, fires, or accidents involving railroad cars and trucks transporting EHSs. Workers and residents in communities surrounding industrial facilities where these substances are manufactured, used, or stored and in communities along the nation's railways and highways are potentially at risk of being exposed to airborne EHSs during accidental releases or intentional releases by terrorists. Pursuant to the Superfund Amendments and Reauthorization Act of 1986, the U.S. Environmental Protection Agency (EPA) has identified approximately 400 EHSs on the basis of acute lethality data in rodents. Acute Exposure Guideline Levels for Selected Airborne Chemicals, Volume 17 identifies, reviews, and interprets relevant toxicologic and other scientific data for selected AEGL documents for acrylonitrile, carbon tetrachloride, cyanogen, epichlorohydrin, ethylene chlorohydrin, toluene, trimethylacetyl chloride, hydrogen bromide, and boron tribromide in order to develop acute exposure guideline levels (AEGLs) for these high-priority, acutely toxic chemicals. AEGLs represent threshold exposure limits (exposure levels below which adverse health effects are not likely to occur) for the general public and are applicable to emergency exposures ranging from 10 minutes (min) to 8 h. Three levels - AEGL-1, AEGL-2, and AEGL-3 - are developed for each of five exposure periods (10 min, 30 min, 1 h, 4 h, and 8 h) and are distinguished by varying degrees of severity of toxic effects. This report will inform planning, response, and prevention in the community, the workplace, transportation, the military, and the remediation of Superfund sites.

Extremely hazardous substances can be released accidentally as a result of chemical spills, industrial explosions, fires, or accidents involving railroad cars and trucks transporting EHSs. Workers and residents in communities surrounding industrial facilities where these substances are manufactured, used, or stored and in communities along the nation's railways and highways are potentially at risk of being exposed to airborne extremely hazardous substances during accidental releases or intentional releases by terrorists. Pursuant to the Superfund Amendments and Reauthorization Act of 1986, the U.S. Environmental Protection Agency has identified approximately 400 extremely hazardous substances on the basis of acute lethality data in rodents. Acute Exposure Guideline Levels for Selected Airborne Chemicals, Volume 16 identifies, reviews, and interprets relevant toxicologic and other scientific data for selected aliphatic nitriles, benzonitrile, methacrylonitrile, allyl alcohol, hydrogen selenide, ketene, and tear gasin order to develop acute exposure guideline levels (AEGLs) for these high-priority, acutely toxic chemicals. AEGLs represent threshold exposure limits (exposure levels below which adverse health effects are not likely to occur) for the general public and are applicable to emergency exposures ranging from 10 minutes (min) to 8 h. Three levels - AEGL-1, AEGL-2, and AEGL-3 - are developed for each of five exposure periods (10 min, 30 min, 1 h, 4 h, and 8 h) and are distinguished by varying degrees of severity of toxic effects. This report will inform planning, response, and prevention in the community, the workplace, transportation, the military, and the remediation of Superfund sites.

At the request of the Department of Defense and the Environmental Protection Agency, the National Research Council has reviewed the relevant scientific literature compiled by an expert panel and established Acute Exposure Guideline Levels (AEGLs) for several chemicals. AEGLs represent exposure levels below which adverse health effects are not likely to occur and are useful in responding to emergencies, such as accidental or intentional chemical releases in community, workplace, transportation, and military settings, and for the remediation of contaminated sites. Three AEGLs are approved for each chemical, representing exposure levels that result in: 1) notable but reversible discomfort; 2) long-lasting health effects; and 3) life-threatening health impacts. Acute Exposure Guideline Levels for Selected Airborne Chemicals: Volume 13 includes AEGLs for boron trifluoride, bromoacetone, chloroacetone, hexafluoroacetone, perchloryl fluoride, piperidine, propargyl alcohol, trimethoxysilane and tetramethoxysilane, and trimethylbenzenes.

Acute Exposure Guideline Levels for Selected Airborne Chemicals, Volume 15 identifies, reviews, and interprets relevant toxicologic and other scientific data for ethyl mercaptan, methyl mercaptan, phenyl mercaptan, tert-octyl mercaptan, lewisite, methyl isothiocyanate, and selected monoisocyanates in order to develop acute exposure guideline levels (AEGLs) for these high-priority, acutely toxic chemicals. AEGLs represent threshold exposure limits (exposure levels below which adverse health effects are not likely to occur) for the general public and are applicable to emergency exposures ranging from 10 minutes (min) to 8 h. Three level—AEGL-1, AEGL-2, and AEGL-3—are developed for each of five exposure periods (10 min, 30 min, 1 h, 4 h, and 8 h) and are distinguished by varying degrees of severity of toxic effects. This report will inform planning, response, and prevention in the community, the workplace, transportation, the military, and the remediation of Superfund sites.

Solar irradiance is a vital source of energy input for the Earth's climate system and its variability has the potential to mitigate or exacerbate a human-created climate. Maintaining an unbroken record of Total Solar Irradiance (TSI) is critical in resolving ongoing debates regarding the potential role of solar variability in influencing Earth's climate. Space-borne instruments have acquired TSI data since 1978. Currently, the best calibrated and lowest noise source of TSI measurements is the Total Irradiance Monitor (TIM) onboard NASA's Solar Radiation and Climate Experiment (SORCE). These TIM-era data are of higher quality than the older data in the full record. Thus, the TSI climate data record (CDR) has two components. There is the shorter, but more accurate record of the TIM era and the full (33+ year) space-based TSI measurement record. Both are important and require preservation. Review of NOAA Working Group Report on Maintaining the Continuation of Long-Term Satellite Total Irradiance Observations evaluates NOAA's plan for mitigating the loss of total solar irradiance measurements from space, given the likelihood of losing this capacity from instruments currently on the SORCE satellite in coming years and the short term/experimental nature of the currently identified method of filling the data gap. This report evaluates NOAA's plan for mitigating the gap in total solar irradiance data.

Climate is changing, forced out of the range of the past million years by levels of carbon dioxide and other greenhouse gases not seen in the Earth's atmosphere for a very, very long time. Lacking action by the world's nations, it is clear that the planet will be warmer, sea level will rise, and patterns of rainfall will change. But the future is also partly uncertain—there is considerable uncertainty about how we will arrive at that different climate. Will the changes be gradual, allowing natural systems and societal infrastructure to adjust in a timely fashion? Or will some of the changes be more abrupt, crossing some threshold or'tipping point'to change so fast that the time between when a problem is recognized and when action is required shrinks to the point where orderly adaptation is not possible? Abrupt Impacts of Climate Change is an updated look at the issue of abrupt climate change and its potential impacts. This study differs from previous treatments of abrupt changes by focusing on abrupt climate changes and also abrupt climate impacts that have the potential to severely affect the physical climate system, natural systems, or human systems, often affecting multiple interconnected areas of concern. The primary timescale of concern is years to decades. A key characteristic of these changes is that they can come faster than expected, planned, or budgeted for, forcing more reactive, rather than proactive, modes of behavior. Abrupt Impacts of Climate Change summarizes the state of our knowledge about potential abrupt changes and abrupt climate impacts and categorizes changes that are already occurring, have a high probability of occurrence, or are unlikely to occur. Because of the substantial risks to society and nature posed by abrupt changes, this report recommends the development of an Abrupt Change Early Warning System that would allow for the prediction and possible mitigation of such changes before their societal impacts are severe. Identifying key vulnerabilities can help guide efforts to increase resiliency and avoid large damages from abrupt change in the climate system, or in abrupt impacts of gradual changes in the climate system, and facilitate more informed decisions on the proper balance between mitigation and adaptation. Although there is still much to learn about abrupt climate change and abrupt climate impacts, to willfully ignore the threat of abrupt change could lead to more costs, loss of life, suffering, and environmental degradation. Abrupt Impacts of Climate Change makes the case that the time is here to be serious about the threat of tipping points so as to better anticipate and prepare ourselves for the inevitable surprises.

Extremely hazardous substances (EHSs) can be released accidentally as a result of result of chemical spills, industrial explosions, fires, or accidents involving railroad cars and trucks transporting EHSs. Workers and residents in communities surrounding industrial facilities where EHSs are manufactured, used, or stored and in communities along the nation's railways and highways are potentially at risk of being exposed to airborne EHSs during accidental releases or intentional releases by terrorists. Pursuant to the Superfund Amendments and Reauthorization Act of 1986, the U.S. Environmental Protection Agency (EPA) has identified approximately 400 EHSs on the basis of acute lethality data in rodents. As part of its efforts to develop acute exposure guideline levels for EHSs, EPA and the Agency for Toxic Substances and Disease Registry (ATSDR) in 1991 requested that the National Research Council (NRC) develop guidelines for establishing such levels. In response to that request, the NRC published Guidelines for Developing Community Emergency Exposure Levels for Hazardous Substances in 1993. Subsequently, Standard Operating Procedures for Developing Acute Exposure Guideline Levels for Hazardous Substances was published in 2001, providing updated procedures, methodologies, and other guidelines used by the National Advisory Committee (NAC) on Acute Exposure Guideline Levels for Hazardous Substances and the Committee on Acute Exposure Guideline Levels (AEGLs) in developing the AEGL values. Using the 1993 and 2001 NRC guidelines reports, the NAC—consisting of members from EPA, the Department of Defense (DOD), the Department of Energy (DOE), the Department of Transportation (DOT), other federal and state governments, the chemical industry, academia, and other organizations from the private sector—has developed AEGLs for more than 270 EHSs. In 1998, EPA and DOD requested that the NRC independently review the AEGLs developed by NAC. In response to that request, the NRC organized within its Committee on Toxicology (COT) the Committee on Acute Exposure Guideline Levels, which prepared this report. This report is the fourteenth volume in that series. Acute Exposure Guideline Levels for Selected Airborne Chemicals: Volume 14 summarizes the committee's conclusions and recommendations.

As climate change has pushed climate patterns outside of historic norms, the need for detailed projections is growing across all sectors, including agriculture, insurance, and emergency preparedness planning. A National Strategy for Advancing Climate Modeling emphasizes the needs for climate models to evolve substantially in order to deliver climate projections at the scale and level of detail desired by decision makers, this report finds. Despite much recent progress in developing reliable climate models, there are still efficiencies to be gained across the large and diverse U.S. climate modeling community. Evolving to a more unified climate modeling enterprise-in particular by developing a common software infrastructure shared by all climate researchers and holding an annual climate modeling forum-could help speed progress. Throughout this report, several recommendations and guidelines are outlined to accelerate progress in climate modeling. The U.S. supports several climate models, each conceptually similar but with components assembled with slightly different software and data output standards. If all U.S. climate models employed a single software system, it could simplify testing and migration to new computing hardware, and allow scientists to compare and interchange climate model components, such as land surface or ocean models. A National Strategy for Advancing Climate Modeling recommends an annual U.S. climate modeling forum be held to help bring the nation's diverse modeling communities together with the users of climate data. This would provide climate model data users with an opportunity to learn more about the strengths and limitations of models and provide input to modelers on their needs and provide a venue for discussions of priorities for the national modeling enterprise, and bring disparate climate science communities together to design common modeling experiments. In addition, A National Strategy for Advancing Climate Modeling explains that U.S. climate modelers will need to address an expanding breadth of scientific problems while striving to make predictions and projections more accurate. Progress toward this goal can be made through a combination of increasing model resolution, advances in observations, improved model physics, and more complete representations of the Earth system. To address the computing needs of the climate modeling community, the report suggests a two-pronged approach that involves the continued use and upgrading of existing climate-dedicated computing resources at modeling centers, together with research on how to effectively exploit the more complex computer hardware systems expected over the next 10 to 20 years.

Tide gauges show that global sea level has risen about 7 inches during the 20th century, and recent satellite data show that the rate of sea-level rise is accelerating. As Earth warms, sea levels are rising mainly because ocean water expands as it warms; and water from melting glaciers and ice sheets is flowing into the ocean. Sea-level rise poses enormous risks to the valuable infrastructure, development, and wetlands that line much of the 1,600 mile shoreline of California, Oregon, and Washington. As those states seek to incorporate projections of sea-level rise into coastal planning, they asked the National Research Council to make independent projections of sea-level rise along their coasts for the years 2030, 2050, and 2100, taking into account regional factors that affect sea level. Sea-Level Rise for the Coasts of California, Oregon, and Washington: Past, Present, and Future explains that sea level along the U.S. west coast is affected by a number of factors. These include: climate patterns such as the El Niño, effects from the melting of modern and ancient ice sheets, and geologic processes, such as plate tectonics. Regional projections for California, Oregon, and Washington show a sharp distinction at Cape Mendocino in northern California. South of that point, sea-level rise is expected to be very close to global projections. However, projections are lower north of Cape Mendocino because the land is being pushed upward as the ocean plate moves under the continental plate along the Cascadia Subduction Zone. However, an earthquake magnitude 8 or larger, which occurs in the region every few hundred to 1,000 years, would cause the land to drop and sea level to suddenly rise.

During the 1980s and 1990s, the National Weather Service (NWS) undertook a major program called the Modernization and Associated Restructuring (MAR). The MAR was officially completed in 2000. No comprehensive assessment of the execution of the MAR plan, or comparison of the promised benefits of the MAR to its actual impact, had ever been conducted. Therefore, Congress asked the National Academy of Sciences to conduct an end-to-end assessment. That report, The National Weather Service Modernization and Associated Restructuring: A Retrospective Assessment, concluded that the MAR was a success. Now, twelve years after the official completion of the MAR, the challenges faced by the NWS are no less important than those of the pre-MAR era. The three key challenges are: 1) Keeping Pace with accelerating scientific and technological advancement, 2) Meeting Expanding and Evolving User Needs in an increasingly information centric society, and 3) Partnering with an Increasingly Capable Enterprise that has grown considerably since the time of the MAR. Weather Services for the Nation presents three main recommendations for responding to these challenges. These recommendations will help the NWS address these challenges, making it more agile and effective. This will put it on a path to becoming second to none at integrating advances in science and technology into its operations and at meeting user needs, leading in some areas and keeping pace in others. It will have the highest quality core capabilities among national weather services. It will have a more agile organizational structure and workforce that allow it to directly or indirectly reach more end-users, save more lives, and help more businesses. And it will have leveraged these capabilities through the broader enterprise. This approach will make possible societal benefits beyond what the NWS budget alone allows.

The U.S. government supports a large, diverse suite of activities that can be broadly characterized as'global change research.'Such research offers a wide array of benefits to the nation, in terms of protecting public health and safety, enhancing economic strength and competitiveness, and protecting the natural systems upon which life depends. The U.S. Global Change Research Program (USGCRP), which coordinates the efforts of numerous agencies and departments across the federal government, was officially established in 1990 through the U.S. Global Change Research Act (GCRA). In the subsequent years, the scope, structure, and priorities of the Program have evolved, (for example, it was referred to as the Climate Change Science Program [CCSP] for the years 2002-2008), but throughout, the Program has played an important role in shaping and coordinating our nation's global change research enterprise. This research enterprise, in turn, has played a crucial role in advancing understanding of our changing global environment and the countless ways in which human society affects and is affected by such changes. In mid-2011, a new NRC Committee to Advise the USGCRP was formed and charged to provide a centralized source of ongoing whole-program advice to the USGCRP. The first major task of this committee was to provide a review of the USGCRP draft Strategic Plan 2012-2021 (referred to herein as'the Plan'), which was made available for public comment on September 30, 2011. A Review of the U.S. Global Change Research Program's Strategic Plan addresses an array of suggestions for improving the Plan, ranging from relatively small edits to large questions about the Program's scope, goals, and capacity to meet those goals. The draft Plan proposes a significant broadening of the Program's scope from the form it took as the CCSP. Outlined in this report, issues of key importance are the need to identify initial steps the Program will take to actually achieve the proposed broadening of its scope, to develop critical science capacity that is now lacking, and to link the production of knowledge to its use; and the need to establish an overall governance structure that will allow the Program to move in the planned new directions.

The Modernization and Associated Restructuring (MAR) of the National Weather Service (NWS) was a large and complex re-engineering of a federal agency. The process lasted a decade and cost an estimated $4.5 billion. The result was greater integration of science into weather service activities and improved outreach and coordination with users of weather information. The MAR created a new, modernized NWS, and, significantly, it created a framework that will allow the NWS to keep up with technological changes in a more evolutionary manner. The MAR was both necessary and generally well executed. However, it required revolutionary, often difficult, changes. The procurement of large, complex technical systems presented challenges in and of itself. The MAR also affected the career paths and personal lives of a large portion of the field office workforce. The MAR created a new, modernized NWS, and, significantly, it created a framework that will allow the NWS to keep up with technological changes in a more evolutionary manner. The National Weather Service Modernization and Associated Restructuring presents the first comprehensive assessment of the execution of the MAR and its impact on the provision of weather services in the United States. This report provides an assessment that addresses the past modernization as well as lessons learned to support future improvements to NWS capabilities.

According to the United Nations, three out of five people will be living in cities worldwide by the year 2030. The United States continues to experience urbanization with its vast urban corridors on the east and west coasts. Although urban weather is driven by large synoptic and meso-scale features, weather events unique to the urban environment arise from the characteristics of the typical urban setting, such as large areas covered by buildings of a variety of heights; paved streets and parking areas; means to supply electricity, natural gas, water, and raw materials; and generation of waste heat and materials. Urban Meteorology: Forecasting, Monitoring, and Meeting Users'Needs is based largely on the information provided at a Board on Atmospheric Sciences and Climate community workshop. This book describes the needs for end user communities, focusing in particular on needs that are not being met by current urban-level forecasting and monitoring. Urban Meteorology also describes current and emerging meteorological forecasting and monitoring capabilities that have had and will likely have the most impact on urban areas, some of which are not being utilized by the relevant end user communities. Urban Meteorology explains that users of urban meteorological information need high-quality information available in a wide variety of formats that foster its use and within time constraints set by users'decision processes. By advancing the science and technology related to urban meteorology with input from key end user communities, urban meteorologists can better meet the needs of diverse end users. To continue the advancement within the field of urban meteorology, there are both short-term needs-which might be addressed with small investments but promise large, quick returns-as well as future challenges that could require significant efforts and investments.

Scientific evidence shows that most glaciers in South Asia's Hindu Kush Himalayan region are retreating, but the consequences for the region's water supply are unclear, this report finds. The Hindu Kush Himalayan region is the location of several of Asia's great river systems, which provide water for drinking, irrigation, and other uses for about 1.5 billion people. Recent studies show that at lower elevations, glacial retreat is unlikely to cause significant changes in water availability over the next several decades, but other factors, including groundwater depletion and increasing human water use, could have a greater impact. Higher elevation areas could experience altered water flow in some river basins if current rates of glacial retreat continue, but shifts in the location, intensity, and variability of rain and snow due to climate change will likely have a greater impact on regional water supplies. Himalayan Glaciers: Climate Change, Water Resources, and Water Security makes recommendations and sets guidelines for the future of climate change and water security in the Himalayan Region. This report emphasizes that social changes, such as changing patterns of water use and water management decisions, are likely to have at least as much of an impact on water demand as environmental factors do on water supply. Water scarcity will likely affect the rural and urban poor most severely, as these groups have the least capacity to move to new locations as needed. It is predicted that the region will become increasingly urbanized as cities expand to absorb migrants in search of economic opportunities. As living standards and populations rise, water use will likely increase-for example, as more people have diets rich in meat, more water will be needed for agricultural use. The effects of future climate change could further exacerbate water stress. Himalayan Glaciers: Climate Change, Water Resources, and Water Security explains that changes in the availability of water resources could play an increasing role in political tensions, especially if existing water management institutions do not better account for the social, economic, and ecological complexities of the region. To effectively respond to the effects of climate change, water management systems will need to take into account the social, economic, and ecological complexities of the region. This means it will be important to expand research and monitoring programs to gather more detailed, consistent, and accurate data on demographics, water supply, demand, and scarcity.

The ocean is a fundamental component of the earth's biosphere. It covers roughly 70 percent of Earth's surface and plays a pivotal role in the cycling of life's building blocks, such as nitrogen, carbon, oxygen, and sulfur. The ocean also contributes to regulating the climate system. Most of the primary producers in the ocean comprise of microscopic plants and some bacteria; and these photosynthetic organisms (phytoplankton) form the base of the ocean's food web. Monitoring the health of the ocean and its productivity is critical to understanding and managing the ocean's essential functions and living resources. Because the ocean is so vast and difficult for humans to explore, satellite remote sensing of ocean color is currently the only way to observe and monitor the biological state of the surface ocean globally on time scales of days to decades. Ocean color measurements reveal a wealth of ecologically important characteristics including: chlorophyll concentration, the rate of phytoplankton photosynthesis, sediment transport, dispersion of pollutants, and responses of oceanic biota to long-term climate changes. Continuity of satellite ocean color data and associated climate research products are presently at significant risk for the U.S. ocean color community. Assessing Requirements for Sustained Ocean Color Research and Operations aims to identify the ocean color data needs for a broad range of end users, develop a consensus for the minimum requirements, and outline options to meet these needs on a sustained basis. The report assesses lessons learned in global ocean color remote sensing from the SeaWiFS/MODIS era to guide planning for acquisition of future global ocean color radiance data to support U.S. research and operational needs.

Climate theory dictates that core elements of the climate system, including precipitation, evapotranspiration, and reservoirs of atmospheric and soil moisture, should change as the climate warms, both in their means and extremes. A major challenge that faces the climate and hydrologic science communities is understanding the nature of these ongoing changes in climate and hydrology and the apparent anomalies that exist in reconciling their extreme manifestations. The National Research Council (NRC) Committee on Hydrologic Science (COHS) held a workshop on January 5-6, 2010, that examined how climate warming translates into hydrologic extremes like floods and droughts. The workshop brought together three groups of experts. The first two groups consisted of atmospheric scientists and hydrologists focused on the scientific underpinnings and empirical evidence linking climate variability to hydrologic extremes. The third group consisted of water managers and decision-makers charged with the design and operation of water systems that in the future must be made resilient in light of a changing climate and an environment of hydrologic extremes. Global Change and Extreme Hydrology summarizes the proceedings of this workshop. This report presents an overview of the current state of the science in terms of climate change and extreme hydrologic events. It examines the'conventional wisdom'that climate change will'accelerate'the hydrologic cycle, fuel more evaporation, and generate more precipitation, based on an increased capacity of a warmer atmosphere to hold more water vapor. The report also includes descriptions of the changes in frequency and severity of extremes, the ability (or inability) to model these changes, and the problem of communicating the best science to water resources practitioners in useful forums.

There is little dispute within the scientific community that humans are changing Earth's climate on a decadal to century time-scale. By the end of this century, without a reduction in emissions, atmospheric CO2 is projected to increase to levels that Earth has not experienced for more than 30 million years. As greenhouse gas emissions propel Earth toward a warmer climate state, an improved understanding of climate dynamics in warm environments is needed to inform public policy decisions. In Understanding Earth's Deep Past, the National Research Council reports that rocks and sediments that are millions of years old hold clues to how the Earth's future climate would respond in an environment with high levels of atmospheric greenhouse gases. Understanding Earth's Deep Past provides an assessment of both the demonstrated and underdeveloped potential of the deep-time geologic record to inform us about the dynamics of the global climate system. The report describes past climate changes, and discusses potential impacts of high levels of atmospheric greenhouse gases on regional climates, water resources, marine and terrestrial ecosystems, and the cycling of life-sustaining elements. While revealing gaps in scientific knowledge of past climate states, the report highlights a range of high priority research issues with potential for major advances in the scientific understanding of climate processes. This proposed integrated, deep-time climate research program would study how climate responded over Earth's different climate states, examine how climate responds to increased atmospheric carbon dioxide and other greenhouse gases, and clarify the processes that lead to anomalously warm polar and tropical regions and the impact on marine and terrestrial life. In addition to outlining a research agenda, Understanding Earth's Deep Past proposes an implementation strategy that will be an invaluable resource to decision-makers in the field, as well as the research community, advocacy organizations, government agencies, and college professors and students.

Emissions of carbon dioxide from the burning of fossil fuels have ushered in a new epoch where human activities will largely determine the evolution of Earth's climate. Because carbon dioxide in the atmosphere is long lived, it can effectively lock the Earth and future generations into a range of impacts, some of which could become very severe. Emissions reductions decisions made today matter in determining impacts experienced not just over the next few decades, but in the coming centuries and millennia. According to Climate Stabilization Targets: Emissions, Concentrations, and Impacts Over Decades to Millennia, important policy decisions can be informed by recent advances in climate science that quantify the relationships between increases in carbon dioxide and global warming, related climate changes, and resulting impacts, such as changes in streamflow, wildfires, crop productivity, extreme hot summers, and sea level rise. One way to inform these choices is to consider the projected climate changes and impacts that would occur if greenhouse gases in the atmosphere were stabilized at a particular concentration level. The book quantifies the outcomes of different stabilization targets for greenhouse gas concentrations using analyses and information drawn from the scientific literature. Although it does not recommend or justify any particular stabilization target, it does provide important scientific insights about the relationships among emissions, greenhouse gas concentrations, temperatures, and impacts. Climate Stabilization Targets emphasizes the importance of 21st century choices regarding long-term climate stabilization. It is a useful resource for scientists, educators and policy makers, among others.

Extremely hazardous substances (EHSs)² can be released accidentally as a result of chemical spills, industrial explosions, fires, or accidents involving railroad cars and trucks transporting EHSs. Workers and residents in communities surrounding industrial facilities where EHSs are manufactured, used, or stored and in communities along the nation's railways and highways are potentially at risk of being exposed to airborne EHSs during accidental releases or intentional releases by terrorists. Pursuant to the Superfund Amendments and Reauthorization Act of 1986, the U.S. Environmental Protection Agency (EPA) has identified approximately 400 EHSs on the basis of acute lethality data in rodents. As part of its efforts to develop acute exposure guideline levels for EHSs, EPA and the Agency for Toxic Substances and Disease Registry (ATSDR) in 1991 requested that the National Research Council (NRC) develop guidelines for establishing such levels. In response to that request, the NRC published Guidelines for Developing Community Emergency Exposure Levels for Hazardous Substances in 1993. Subsequently, Standard Operating Procedures for Developing Acute Exposure Guideline Levels for Hazardous Substances was published in 2001, providing updated procedures, methodologies, and other guidelines used by the National Advisory Committee (NAC) on Acute Exposure Guideline Levels for Hazardous Substances and the Committee on Acute Exposure Guideline Levels (AEGLs) in developing the AEGL values. In 1998, EPA and DOD requested that the NRC independently review the AEGLs developed by NAC. In response to that request, the NRC organized within its Committee on Toxicology (COT) the Committee on Acute Exposure Guideline Levels, which prepared this report. Acute Exposure Guideline Levels for Selected Airborne Chemicals is the tenth volume of the series and documents for N,N-dimethylformamide, jet propellant fuels 5 and 8, methyl ethyl ketone, perchloromethyl mercaptan, phosphorus oxychloride, phosphorus trichloride, and sulfuryl chloride.

Climate change is occurring. It is very likely caused by the emission of greenhouse gases from human activities, and poses significant risks for a range of human and natural systems. And these emissions continue to increase, which will result in further change and greater risks. America's Climate Choices makes the case that the environmental, economic, and humanitarian risks posed by climate change indicate a pressing need for substantial action now to limit the magnitude of climate change and to prepare for adapting to its impacts. Although there is some uncertainty about future risk, acting now will reduce the risks posed by climate change and the pressure to make larger, more rapid, and potentially more expensive reductions later. Most actions taken to reduce vulnerability to climate change impacts are common sense investments that will offer protection against natural climate variations and extreme events. In addition, crucial investment decisions made now about equipment and infrastructure can'lock in'commitments to greenhouse gas emissions for decades to come. Finally, while it may be possible to scale back or reverse many responses to climate change, it is difficult or impossible to'undo'climate change, once manifested. Current efforts of local, state, and private-sector actors are important, but not likely to yield progress comparable to what could be achieved with the addition of strong federal policies that establish coherent national goals and incentives, and that promote strong U.S. engagement in international-level response efforts. The inherent complexities and uncertainties of climate change are best met by applying an iterative risk management framework and making efforts to significantly reduce greenhouse gas emissions; prepare for adapting to impacts; invest in scientific research, technology development, and information systems; and facilitate engagement between scientific and technical experts and the many types of stakeholders making America's climate choices.